Study of magnetic, dielectric and magnetodielectric properties of BaTiO3/Fe3O4 core/shell nanocomposite

Abstract

Multiferroic systems fashioned by involvement of a ferroelectric phase and a ferromagnetic phase have received significant attention because of their wide possibilities for tailoring properties. However, many interrogations persist about how the structure and chemistry of interface mediates magnetodielectric activities. In this study, we have explored the magnetic, dielectric and magnetodielectric behavior of BaTiO3/Fe3O4 core/shell nanocomposite synthesized by combined co-precipitation cum sonochemical method. The phase formation of the core/shell naonocomposite was confirmed independently from X-ray diffraction and selected area electron diffraction studies. The microstructure of the sample was studied by transmission electron microscopy and High resolution TEM revealing a good mixing of two phases in the form of core (BaTiO3)/shell (Fe3O4). Magnetic property of the sample was investigated using a vibrating sample magnetometer (VSM) at room temperature. The magnetic study reveals that the synthesized core/shell nanocompositeis ferromagnetic with saturation magnetization of ~58 emu/g. The dielectric constant of the core/shell nanocomposite, measured as a function of temperature, at frequencies 1, 10, 100, 500 and 1 MHz combines almost the characteristics of BaTiO3 and Fe3O4 in accordance with the Maxwell–Garnett equation. However, near 125 K a clear hump is observed probably due to characteristic Verwey transition (TV) in Fe3O4. The dielectric constant also shows dispersion behavior with increasing frequency due to Maxwell–Wagner interfacial polarization. Furthermore, the shrinkagein dielectric constant (at 20 K) on the application of 1 T external magnetic field depicts the possible coupling between the dielectric (BaTiO3) and the magnetic (Fe3O4) phases of BaTiO3/Fe3O4 core/shell nanocomposite.